On-axis mounting of an inertial measurement unit (IMU) within an optical system

ABSTRACT

Techniques and architecture are disclosed for providing an optical system having an on-axis, internally mounted inertial measurement unit (IMU). In some cases, an IMU may be mounted within an interior region/cavity of an inner housing, which intern is configured to rotate within an outer housing. In some instances, a mirror assembly may be operatively coupled with the inner housing and permitted to rotate simultaneously with the IMU. Rotation of the inner housing may be achieved, in some example cases, by use of a suitable motor. In some instances, positioning componentry may be operatively coupled with one or more of the IMU and/or mirror assembly. Improvements in mechanical stability, system dimensions, and/or protection from external/environmental hazards may be realized, in some example cases.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 13/608,087filed Sep. 10,2012 and claims the benefit of U.S. Provisional PatentApplication No. 61/534,049, filed on Sep. 13,2011, which is hereinincorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The invention relates to optical systems, and more particularly toinertial measurement unit (IMU) mounting for an optical system.

BACKGROUND

Optical systems involve a number of non-trivial challenges, and opticalsystems including inertial measurement units (IMUs) have facedparticular complications.

SUMMARY

One example embodiment of the present invention provides a systemincluding a first housing having a first cavity provided therein, asecond housing having a second cavity provided therein, wherein thesecond housing is disposed within the first cavity and permitted torotate therein, and an optical assembly operatively coupled with thesecond housing, wherein rotation of the second housing results inrotation of the optical assembly therewith. In some cases, the systemfurther includes an inertial measurement unit (IMU) operatively coupledwith the second housing and positioned within the second cavity, whereinrotation of the second housing results in rotation of the IMU therewith.In some such cases, the system further includes a mounting site providedwithin the second cavity, wherein the IMU is operatively coupled withthe second housing at the mounting site. In some other such cases, theIMU is operatively coupled with the second housing along an azimuthalaxis of the system. In some instances, the optical assembly includes anoptical sensor, a mirror configured to direct light to the opticalsensor, an optical assembly motor operatively coupled with the mirrorand configured to cause movement thereof, and an optical assemblyencoder operatively coupled with the optical assembly motor andconfigured to communicate therewith. In some such instances, the mirrorincludes at least one of a stabilized mirror, a tilt mirror, and/or atwo-axis mirror. In some example cases, the system further includes adrive assembly operatively coupled with the second housing andconfigured to cause rotation thereof within the first housing. In somesuch cases, the drive assembly includes a first bridge assemblyincluding a first arrangement of bearings, a second bridge assemblyincluding a second arrangement of bearings, a drive shaft positionedbetween the first and second bridge assemblies and operatively coupledwith the second housing, a drive assembly motor operatively coupled withthe drive shaft and configured to cause rotation thereof, and a driveassembly encoder operatively coupled with the drive assembly motor andconfigured to communicate therewith. In some such instances, at leastone of the first arrangement of bearings and/or the second arrangementof bearings includes duplex bearings, and the drive shaft ispositionable within an inner race of such duplex bearings. In some othersuch instances, the first and second arrangements of bearings includeduplex bearings, wherein one of the first and second arrangements ofbearings is clamped axially while the other of the first and secondarrangements of bearings remains unclamped. In some cases, the systemfurther includes a base assembly operatively coupled with the firsthousing, wherein the base assembly includes at least one of a thermalisolator and/or a power supply interface. In some example cases, thesecond housing is permitted to rotate through an angle in the range ofless than or equal to about ±40°. In some instances, the system isconfigured to be operatively coupled with at least one of a chassis, apiece of equipment, a vehicle, a building, and/or a bunker. In someinstances, the system is environmentally sealed.

Another example embodiment of the present invention provides a systemincluding a first housing having a first cavity provided therein, asecond housing having a second cavity provided therein, wherein thesecond housing is disposed within the first cavity and permitted torotate therein, an optical assembly operatively coupled with the secondhousing, an inertial measurement unit (IMU) operatively coupled with thesecond housing and positioned within the second cavity, and a drivemotor operatively coupled with the second housing and configured tocause rotation thereof, wherein rotation of the second housing resultsin rotation of the optical assembly and the IMU therewith. In somecases, the second housing is permitted to rotate through an angle in therange of less than or equal to about ±40°. In some instances, theoptical assembly is permitted to rotate about at least one of anazimuthal axis of the system and/or an elevation axis of the system, andthe IMU is permitted to rotate about the azimuthal axis of the system.In some example cases, the IMU is configured to account for effects ofrotation on measurements that it makes. In some example instances, theIMU is a one-axis, two-axis, or three-axis IMU.

Another example embodiment of the present invention provides a systemincluding a first housing having a first cavity provided therein, asecond housing having a second cavity provided therein, wherein thesecond housing is disposed within the first cavity and permitted torotate therein, an inertial measurement unit (IMU) operatively coupledwith the second housing and positioned within the second cavity, amirror operatively coupled with the second housing, an elevation motoroperatively coupled with the mirror and configured to cause rotationthereof about an elevation axis of the system, and an azimuthal motoroperatively coupled with the second housing and configured to causerotation thereof about an azimuth axis of the system, wherein rotationof the second housing results in rotation of the mirror and the IMUtherewith about the azimuth axis of the system.

The features and advantages described herein are not all-inclusive and,in particular, many additional features and advantages will be apparentto one of ordinary skill in the art in view of the drawings,specification, and claims. Moreover, it should be noted that thelanguage used in the specification has been selected principally forreadability and instructional purposes and not to limit the scope of theinventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are a front perspective and front cross-sectional view,respectively, of a system configured in accordance with an embodiment ofthe present invention.

FIGS. 2A and 2B are a side perspective and a side cross-sectional view,respectively, of a system configured in accordance with an embodiment ofthe present invention.

FIG. 3 is a perspective view of an outer housing configured inaccordance with an embodiment of the present invention.

FIG. 4 is an exploded perspective view of an optional base assemblyconfigured in accordance with an embodiment of the present invention.

FIG. 5 is a perspective view of an inner housing configured inaccordance with an embodiment of the present invention.

FIG. 6 is an exploded perspective view of an inertial measurement unit(IMU) and an optional capping plate configured in accordance with anembodiment of the present invention.

FIG. 7 is a top-down perspective view of a system configured inaccordance with an embodiment of the present invention.

These and other features of the present embodiments will be understoodbetter by reading the following detailed description, taken togetherwith the figures herein described. The accompanying drawings are notintended to be drawn to scale. In the drawings, each identical or nearlyidentical component that is illustrated in various figures isrepresented by a like numeral. For purposes of clarity, not everycomponent may be labeled in every drawing.

DETAILED DESCRIPTION

Techniques and architecture are disclosed for providing an opticalsystem having an on-axis, internally mounted inertial measurement unit(IMU). In some cases, an IMU may be mounted within an interiorregion/cavity of an inner housing, which in turn is configured to rotatewithin an outer housing. In some instances, a mirror assembly may beoperatively coupled with the inner housing and permitted to rotatesimultaneously with the IMU. Rotation of the inner housing may beachieved, in some example cases, by use of a suitable motor. In someinstances, positioning componentry may be operatively coupled with oneor more of the IMU and/or mirror assembly. Improvements in mechanicalstability, system dimensions, and/or protection fromexternal/environmental hazards may be realized, in some example cases.Numerous configurations and variations will be apparent in light of thisdisclosure.

General Overview

As previously indicated, there are a number of non-trivial issues thatcan arise which complicate optical systems including inertialmeasurement units (IMUs). For instance, one non-trivial issue pertainsto the fact that existing optical systems require external mounting ofan IMU. As will be appreciated in light of this disclosure, external IMUmounting increases the length and footprint of a given optical system.As will be further appreciated, external mounting of the IMU affords noprotection thereof from the surrounding environment. Still further,external mounting of an IMU decreases the mechanical stability of agiven optical system.

Thus, and in accordance with an embodiment of the present invention,techniques and architecture are disclosed for providing an opticalsystem having an on-axis, internally mounted inertial measurement unit(IMU). In some such cases, and in accordance with an embodiment, thesystem may include an inner housing configured to house an IMU (and/orother electronics/componentry) and to rotate within an outer housing ofthe system, for example, about the azimuth axis of the system. Inaccordance with an embodiment, effects of such rotation, if any, onmeasurements made by the IMU may be accounted for by the IMU. In someinstances, a mirror assembly may be operatively coupled with the innerhousing and thus permitted to rotate simultaneously with the IMU.

Rotation of the inner housing, and thus the IMU and/or mirror assembly,may be achieved, in some example cases, by use of a suitable motor, inaccordance with an embodiment. In some embodiments, positioningcomponentry may be operatively coupled with one or more of the IMUand/or mirror assembly.

Some embodiments of a system provided using the disclosedtechniques/architecture may exhibit improvements/enhancements inmechanical stability as compared to existing designs/approaches. Also,some embodiments of a system provided using the disclosedtechniques/architecture may realize a reduction in overall length and/orfootprint. Furthermore, some embodiments of a system provided using thedisclosed techniques/architecture may have improved/enhanced protection,in part or in full, from environmental hazards as compared with existingdesigns/approaches.

System Architecture and Operation FIGS. 1A and 1B are a frontperspective and front cross-sectional view, respectively, of a system1000 configured in accordance with an embodiment of the presentinvention. FIGS. 2A and 2B are a side perspective and a sidecross-sectional view, respectively, of a system 1000 configured inaccordance with an embodiment of the present invention. As can be seenfrom these figures, system 1000 may include, for example, an outerhousing 100 and an inner housing 300 configured to be positioned, atleast in part, within outer housing 100. Inner housing 300 can beconfigured to house any of a number of electronics/components of system1000, such as, but not limited to, an inertial measurement unit (IMU)400. In some such cases, IMU 400 may be mounted on-axis within innerhousing 300. Also, inner housing 300 can be operatively coupled with anazimuth motor 430 via a drive shaft 630 and thus be provided with theability to rotate within outer housing 100, as discussed below. In somecases, system 1000 may include one or more optical components, such as,but not limited to: (1) a mirror assembly 500; (2) an azimuthpositioning assembly (e.g., azimuth encoder 440, azimuth motor 430,etc.); and/or (3) an elevation positioning assembly (e.g., elevationencoder 540, elevation motor 530, etc.). As will be appreciated in lightof this disclosure, system 1000 may include additional, fewer, and/ordifferent elements or components from those here described (e.g.,optional base assembly 200, etc.), and the claimed invention is notintended to be limited to any particular system configurations, but canbe used with numerous configurations in numerous applications.

FIG. 3 is a perspective view of an outer housing 100 configured inaccordance with an embodiment of the present invention. As can be seen,in some embodiments, outer housing 100 may be generally configured as ahollow, substantially cylindrical body 110 (e.g., having a substantiallycircular cross-sectional geometry) having one or more open ends and aninternal region 120 defined there between. In some embodiments, outerhousing 100 may be configured, for example, to be operatively coupledwith an optional base assembly 200 (discussed below with reference toFIG. 4). To that end, outer housing 100 may be provided, in someembodiments, with a flanged (or otherwise rimmed) portion 112, which mayinclude one or more fastening apertures 113 configured for receivingsuitable fasteners for operatively coupling outer housing 100 with anoptional base assembly 200 (and/or other structure). However, as will beappreciated in light of this disclosure, outer housing 100 may beoperatively coupled with an optional base assembly 200 (and/or otherstructure) without use of a flanged portion 112, in some otherembodiments.

In some cases, a mounting flange (or otherwise rimmed portion) 114 maybe provided, for example, on the exterior of body 110. In accordancewith an embodiment, mounting flange 114 may be configured to permitouter housing 100 (e.g., and thus system 1000) to be operatively coupled(e.g., mounted or otherwise attached) with one or more externalstructures (e.g., a chassis, piece of equipment, vehicle, building,bunker, etc.). Mounting flange 114 may be provided with one or morefastening apertures 115 configured for receiving suitable fasteners foroperatively coupling outer housing 100 with such an external structure.However, as will be appreciated in light of this disclosure, outerhousing 100 may be operatively coupled with a desired external structurewithout use of a mounting flange 114, in some other embodiments.

In accordance with an embodiment, the dimensions (e.g., outer and/orinner diameters; length/height; etc.) of outer housing 100 may becustomized for a given application. In some embodiments, outer housing100 may be dimensioned such that an inner housing 300 (discussed belowwith reference to FIG. 5) may be positioned within internal region 120thereof. In some such cases, the inner diameter of outer housing 100 maybe sufficiently large, for example, to allow inner housing 300 to rotatetherein (as discussed below with reference to FIG. 7). Also, outerhousing 100 may be dimensioned, in some example instances, such that itsinternal region 120 may house one or more other portions of system 1000(e.g., a lower bridge assembly 620, a portion of a drive shaft 630, anazimuth motor 430, etc., discussed below).

As will be appreciated, outer housing 100 may be configured to assistwith protecting components, structures, electronics, etc., of system1000 which may be housed therein. Thus, and in accordance with anembodiment, it may be desirable to ensure that outer housing 100 isconstructed with material(s) having sufficient structural strength. Someexample suitable materials may include, but are not limited to: (1)titanium (Ti); (2) aluminum (Al); (3) steel; (4) an alloy of theaforementioned; and/or (5) any other suitable material/metal as will beapparent in light of this disclosure. Other suitable configurations,dimensions, materials, and/or structural considerations for outerhousing 100 will depend on a given application and will be apparent inlight of this disclosure.

As previously noted, outer housing 100 may be operatively coupled withan optional base assembly 200 in some embodiments. FIG. 4 is an explodedperspective view of an optional base assembly 200 configured inaccordance with an embodiment of the present invention. As can be seen,optional base assembly 200 may include, for example, a housing base 210,a base plate 230, a thermal isolator 240, and/or an interface 250. Othersuitable components and/or configurations for optional base assembly200, when included, will depend on a given application and will beapparent in light of this disclosure.

When included, housing base 210 may be generally configured as a hollow,substantially cylindrical body (e.g., having a substantially circularcross-sectional geometry) having one or more open ends and an internalregion 220 defined there between. In some embodiments, housing base 210may be configured, for example, to be operatively coupled with outerhousing 200 at an end thereof (as previously discussed). To that end,housing base 210 may be provided, in some embodiments, with a flanged(or otherwise rimmed) portion 212, which may include one or morefastening apertures 213 configured for receiving suitable fasteners foroperatively coupling housing base 210 with outer housing 100. However,as will be appreciated in light of this disclosure, housing base 210 maybe operatively coupled with outer housing 100 without use of a flangedportion 212, in some other embodiments.

In accordance with an embodiment, the dimensions (e.g., outer and/orinner diameters; length/height; etc.) of housing base 210 may becustomized for a given application. In some embodiments, housing base210 may be dimensioned with an outer and/or inner diameter whichsubstantially matches that/those of outer housing 100. Also, housingbase 210 may be dimensioned, in some example instances, to house one ormore other portions of system 1000 (e.g., a lower bridge assembly 620, aportion of a drive shaft 640, an azimuth motor 430, etc., discussedbelow). When included, housing base 210 may be configured so as to notinterfere with or otherwise affect the ability of inner housing 300 torotate within outer housing 100.

Much like outer housing 100, housing base 210 may be configured toassist with protecting components, structures, electronics, etc., ofsystem 1000 which may be housed therein. Thus, and in accordance with anembodiment, it may be desirable to ensure that housing base 210 isconstructed with material(s) having sufficient structural strength. Someexample suitable materials may include, but are not limited to, any oneor more of those discussed above with reference to outer housing 100. Insome cases, and in accordance with an embodiment, it may be desirable toconstruct housing base 210 from the same material(s), for example, asouter housing 100 to help minimize (or otherwise reduce) complicationswhich otherwise may result from coefficient of thermal expansion (CTE)mismatching. Other suitable configurations, dimensions, materials,and/or structural considerations for housing base 210, when included,will depend on a given application and will be apparent in light of thisdisclosure.

In some cases, optional base assembly 200 may include a thermal isolator240 configured to be disposed, for example, between housing base 210 andouter housing 100. Thermal isolator 240 may be configured to assist withpreventing (or otherwise reducing) heat transfer, for example, fromouter housing 100 (and/or any components housed thereby or operativelycoupled therewith) to housing base 210 (and/or any components containedtherein or operatively coupled therewith). Thus, and in accordance withan embodiment, it may be desirable to ensure that thermal isolator 240is constructed with material(s) having sufficient thermal insulationcapabilities. Some example suitable materials may include, but are notlimited to: (1) glass-reinforced epoxy laminate (e.g., G10 plastic); (2)fiberglass; (3) printed circuit board (PCB) material; (4) a combinationof the aforementioned; and/or (5) any other suitable thermal insulatingmaterial as will be apparent in light of this disclosure.

In accordance with an embodiment, the dimensions of thermal isolator 240may be customized for a given application. In some embodiments, thermalisolator 240 may be dimensioned with an outer and/or inner diameterwhich substantially matches that/those of outer housing 100 and/orhousing base 210. Also, thermal isolator 240 may include (or otherwisebe capable of having formed therein) one or more fastening apertures 241configured for receiving suitable fasteners for positioning/securingthermal isolator 240 between outer housing 100 and housing base 210.When included, thermal isolator 240 may be configured so as to notinterfere with or otherwise affect the ability of inner housing 300 torotate within outer housing 100. Other suitable configurations,materials, and/or structural considerations for thermal isolator 240will depend on a given application and will be apparent in light of thisdisclosure.

In some cases, optional base assembly 200 may include a base plate 230configured to be operatively coupled, for example, with an open end ofhousing base 210 (e.g., an open end of housing base 210 which is not tobe operatively coupled with outer housing 100). Base plate 230 may beconfigured, for example, to assist with protecting any components whichmay be housed or otherwise provided within housing base 210 bysealing/closing an open end of housing base 210. In some cases, baseplate 230 may be configured to assist with providing housing base 210(and thus system 1000) with a desired degree of environmental sealing.However, as will be appreciated, base plate 230 alternatively may beconfigured to seal/close an end of housing base 210 without providing anenvironmental seal, in some other embodiments. Thus, and in accordancewith an embodiment, it may be desirable to ensure that base plate 230 isconstructed with material(s) having sufficient structural strength. Someexample suitable materials may include, but are not limited to, any oneor more of those discussed above with reference to housing base 210. Insome cases, and in accordance with an embodiment, it may be desirable toconstruct base plate 230 from the same material(s), for example, ashousing base 210 to help minimize (or otherwise reduce) complicationswhich otherwise may result from coefficient of thermal expansion (CTE)mismatching.

In accordance with an embodiment, the dimensions of base plate 230 maybe customized for a given application. In some embodiments, base plate230 may be dimensioned with a diameter/width which substantially matchesthat of housing base 210. Also, base plate 230 may include one or morefastening apertures 231 configured for receiving suitable fasteners foroperatively coupling base plate 230 with housing base 210. Whenincluded, base plate 230 may be configured so as to not interfere withor otherwise affect the ability of inner housing 300 to rotate withinouter housing 100. Other suitable configurations, materials, and/orstructural considerations for base plate 230 will depend on a givenapplication and will be apparent in light of this disclosure.

In some cases, optional base assembly 200 may include an interface 250configured to be operatively coupled with external componentry (e.g., apower supply, a data processor, etc.). In some embodiments, interface250 may be formed in or otherwise operatively coupled, for example, withhousing base 210. In some instances, interface 250 may be configured tobe operatively coupled with one or more power supplies, for example, forpowering any of the components of system 1000 (e.g., IMU 400, azimuthmotor 430, azimuth encoder 440, elevation motor 530, and/or elevationencoder 540, etc.). In some instances, interface 250 may be configuredto be operatively coupled with one or more data processing components,for example, for processing data provided by any of the components ofsystem 1000 (e.g., IMU 400, azimuth motor 430, azimuth encoder 440,elevation motor 530, and/or elevation encoder 540, etc.). Other suitableconfigurations and/or capabilities of interface 250 will depend on agiven application and will be apparent in light of this disclosure.

FIG. 5 is a perspective view of an inner housing 300 configured inaccordance with an embodiment of the present invention. As can be seen,in some embodiments, inner housing 300 may be generally configured as ahollow, substantially cylindrical body 310 (e.g., having a substantiallycircular cross-sectional geometry) having one or more open ends. In somecases, one or more of the ends of inner housing 300 may be sealed orotherwise closed, for example, by: (1) constructing inner housing 300 tohave a continuous end wall which provides an integral end surface 312;and/or (2) operatively coupling an appropriate structure (e.g., a platesimilar to the base plate 230 described above; a capping plate 333,discussed below; etc.) with inner housing 300 to provide end surface312. In some instances, end surface 312 (whether integral to innerhousing 300 or operatively coupled thereto) may be flanged or otherwiserimmed, such as can be seen with particular reference to FIG. 5. In somesuch cases, a flanged end surface 312 may be configured to rest on orotherwise be proximate to a given end of outer housing 100, as can beseen best from FIGS. 1B and 2B.

In accordance with an embodiment, the dimensions (e.g., outer and/orinner diameters; length/height; etc.) of inner housing 300 may becustomized for a given application. In some embodiments, inner housing300 may be dimensioned such that it may be positioned, at least in part,within outer housing 100 (e.g., within internal region 120) andpermitted to extend out of one or more ends of the outer housing 100. Insome such cases, the outer diameter of inner housing 300 may bedimensioned sufficiently smaller, for example, than the inner diameterof outer housing 100 to allow inner housing 300 to rotate withininternal region 120 of outer housing 100 (as discussed below withreference to FIG. 7). Also, inner housing 300 may be dimensioned, insome example instances, to house one or more other portions of system1000 (e.g., IMU 400, mounting site 410, support bar 332, connector 334,etc., discussed below with reference to FIG. 6).

As can be seen from FIG. 5, for example, inner housing 300 may beprovided with an internal cavity 320. In accordance with an embodiment,internal cavity 320 may be configured to house and/or protectcomponentry (e.g., IMU 400, etc.) of system 1000 which may be disposedtherein. In some instances, internal cavity 320 may constitute asubstantial portion (e.g., greater than 50%; greater than 60%; greaterthan 70%; greater than 80%; etc.) of the volume of inner housing 300. Insome embodiments, internal cavity 320 may be partitioned or otherwisecompartmentalized, in part or in whole. Other suitable configurationsand/or considerations for internal cavity 320 will depend on a givenapplication and will be apparent in light of this disclosure.

As can be seen in FIGS. 1A-1B, for example, inner housing 300 may beconfigured with one or more projections/arms 330, 340, etc., extendingtherefrom (e.g., in the direction substantially opposite the location ofinternal cavity 320). In some instances, the one or more projections330/340 may be integral with end surface 312 (e.g., depicted in FIG. 5),while in some other instances, projections 330/340 may be operativelycoupled with end surface 312. In some cases in which two or moreprojections 330/340 are provided, such projections 330/340 may bedistally spaced from one another (e.g., across the breadth of endsurface 312). As can further be seen from the figures, projections330/340 may be configured, for example, to have a mirror assembly 500(discussed below) operatively coupled there between. Other suitableconfigurations and/or considerations for the one or more projections330/340 will depend on a given application and will be apparent in lightof this disclosure.

In accordance with an embodiment, inner housing 300 may be configured toassist with: (1) protecting components, structures, electronics, etc.,of system 1000 which may be housed therein; and/or (2) supportingcomponents, structures, electronics, etc., of system 1000 which may beoperatively coupled therewith. Thus, and in accordance with anembodiment, it may be desirable to ensure that inner housing 300 isconstructed with material(s) having sufficient structural strength. Someexample suitable materials may include, but are not limited to, any oneor more of those discussed above with reference to outer housing 100. Aswill be appreciated, it may be desirable to ensure that inner housing300 is made from the same material(s), for example, as outer housing 100to minimize (or otherwise reduce) complications which may arise fromcoefficient of thermal expansion (CTE) mismatching. Other suitableconfigurations, dimensions, materials, and/or structural considerationsfor inner housing 300 will depend on a given application and will beapparent in light of this disclosure.

As previously noted, in some cases a mirror assembly 500 may beoperatively coupled, for example, with the one or more of projections330/340 of inner housing 300. In some example embodiments, mirrorassembly 500 may include a mirror 510 and/or a bezel 520 operativelycoupled with the mirror 510 and configured to assist with operativelycoupling mirror 510 with system 1000 (e.g., between projections330/340). Mirror 510 may be configured to direct incident light onto anoptical sensor of system 1000. Any suitable mirror 510 may beimplemented, and some example types may include, but are not limited to:(1) a stabilized mirror; (2) a tilt mirror; and/or (3) a two-axismirror. By virtue of how it is operatively coupled with inner housing300 (e.g., at projections 330/340), mirror 510 may be configured tofunction along the roll axis and/or along the pitch axis. As can be seenfrom FIG. 1B, for example, mirror assembly 500 may be permitted torotate, in part or in whole, about an elevation axis and/or an azimuthaxis of system 1000.

In some cases, mirror assembly 500 may be operatively coupled, forexample, with one or more elevation positioning components. Forinstance, in some embodiments, mirror assembly 500 may be operativelycoupled with: (1) an elevation motor 530; and/or (2) an elevationencoder 540. When included, elevation motor 530 may be positioned on orotherwise operatively coupled, for example, with a projection 330 ofinner housing 300. In accordance with an embodiment, elevation motor 530may be configured to engage mirror assembly 500 to change itsposition/orientation (e.g., elevation, pitch, etc.). Similarly,elevation encoder 540 may be positioned on or otherwise operativelycoupled, for example, with a projection 340 of inner housing 300. Inaccordance with an embodiment, elevation encoder 540 may be configuredto measure or otherwise determine the position/orientation (e.g.,elevation, pitch, etc.) of mirror assembly 500. In some cases, elevationencoder 540 may be operatively coupled, for example, with electroniccomponentry (e.g., a computer or other data acquisition device)configured to receive positioning/orientation data from elevationencoder 540. As will be appreciated, such componentry may be configuredto subsequently transmit data/instructions to elevation motor 530, forexample, to change the positioning/orientation of mirror assembly 500.Other suitable configurations and/or considerations for elevation motor530 and/or elevation encoder 540 will depend on a given application andwill be apparent in light of this disclosure.

FIG. 6 is an exploded perspective view of an inertial measurement unit(IMU) 400 and an optional capping plate 330 configured in accordancewith an embodiment of the present invention. As previously noted, insome cases an IMU 400 may be operatively coupled, for example, withinner housing 300. In some specific example instances, IMU 400 may beconfigured to be disposed within internal cavity 320 of inner housing300. In accordance with an embodiment, system 1000 may be configured,for example, for internal, on-axis mounting of an IMU 400 (as can beseen with particular reference to FIGS. 1B and 2B).

As used herein, an inertial measurement unit (IMU) 400 may refer to adevice that can measure and/or report on inertial rotation rates and/orinertial acceleration in system 1000. In some embodiments, IMU 400 mayinclude one or more accelerometers, gyroscopes, and/or magnetometers.IMU 400 may be configured, in accordance with an embodiment, to detectchanges in pitch, roll, and/or yaw in a system 1000. In some such cases,these types of changes may be detected in one, two, and/or threedimensions (e.g., a one-axis, two-axis, and/or three-axis IMU) in asimultaneous or separate fashion. In some specific example cases, IMU400 may include or otherwise be operatively coupled with an inertialnavigation system (INS). Other suitable configurations for an IMU 400will depend on a given application and will be apparent in light of thisdisclosure.

As can be seen with reference to FIGS. 5 and 6, for example, by virtueof placement within inner housing 300 (and thus outer housing 100), insome embodiments IMU 400 may be protected from external environmentalhazards. In some cases, IMU 400 may be operatively coupled with endsurface 312 (e.g., on the side of end surface 312 which defines, inpart, the bounds of internal cavity 320). In accordance with anembodiment, IMU 400 may be configured to function, for example: (1) onthe azimuth axis; and/or (2) on the pitch axis. Also, as discussedbelow, and in accordance with an embodiment, IMU 400 may be permitted torotate on the azimuth axis of system 1000 by virtue of its operativecoupling with inner housing 300.

In some cases, a mounting site 410 may be provided for operativelycoupling IMU 400 (and/or other electronics/components) with innerhousing 300. As can be seen with reference to FIGS. 5 and 6, forexample, mounting site 410 may be configured to be disposed withininternal cavity 320 of inner housing 300. In some example instances,mounting site 410 may be operatively coupled with end surface 312 (e.g.,on the side of end surface 312 which defines, in part, the bounds ofinternal cavity 320) and configured to have IMU 400 operatively coupledtherewith. In some other example instances, mounting site 410 may beintegral to inner housing 300 (e.g., integral with end surface 312 andoriented toward internal cavity 320) and configured to have IMU 400operatively coupled therewith. Other suitable configurations and/orconsiderations for mounting site 410 will depend on a given applicationand will be apparent in light of this disclosure.

As previously noted, it may be desirable in some cases to seal/close agiven open end of inner housing 300. To that effect, and in accordancewith an embodiment, a capping plate 330 may be operatively coupled witha given open end of inner housing 300. In some cases, a capping plate330 may be operatively coupled with (e.g., fastened to, seated on, etc.)the open end opposite the sealed/closed end surface 312 while positionedwithin internal region 120 of outer housing 100. Capping plate 330 maybe configured, for example, to assist with protecting any componentswhich may be housed or otherwise provided within internal cavity 320 ofinner housing 300 by sealing/closing an open end of inner housing 300.

In accordance with an embodiment, the dimensions (e.g., diameter/width;thickness; etc.) of capping plate 330 may be customized for a givenapplication. In some embodiments, capping plate 330 may be dimensionedwith a diameter/width which: (1) substantially matches that of the endof inner housing 300 with which it is to be operatively coupled; and/or(2) is sufficiently smaller, for example, than the inner diameter ofouter housing 100 (e.g., the diameter of internal region 120) topreserve the ability of inner housing 300 to rotate within outer housing100 (as discussed below with reference to FIG. 7). Also, capping plate330 may include one or more fastening apertures 331 configured forreceiving suitable fasteners for operatively coupling capping plate 330with inner housing 300. When included, capping plate 330 may beconfigured so as to not interfere with or otherwise affect the abilityof inner housing 300 to rotate within outer housing 100.

In some cases, a support bar 332 may be provided, for example, to assistwith supporting wiring and/or electronics to be positioned withininternal cavity 320. In some instances, support bar 332 may beoperatively coupled with capping plate 330 and configured to extend intointernal cavity 320 to a given depth (e.g., the entire depth of internalcavity 320 or some lesser depth thereof). In some other instances,support bar 332 may be integral with capping plate 330 and configured toextend into internal cavity 320. In some embodiments, support bar 332may include a connector 334 operatively coupled therewith forinterfacing with any electronic componentry which may be disposed withininternal cavity 320 (e.g., IMU 400, etc.).

In accordance with an embodiment, capping plate 330 may be configured toassist with protecting components, structures, electronics, etc., ofsystem 1000 which may be housed within internal cavity 320 of innerhousing 300. Thus, and in accordance with an embodiment, it may bedesirable to ensure that capping plate 330 is constructed withmaterial(s) having sufficient structural strength. Some example suitablematerials may include, but are not limited to, any one or more of thosediscussed above with reference to inner housing 300. In some cases, andin accordance with an embodiment, it may be desirable to constructcapping plate 330 (and support bar 332, when included) from the samematerial(s), for example, as inner housing 300 to help minimize (orotherwise reduce) complications which otherwise may result fromcoefficient of thermal expansion (CTE) mismatching. Other suitableconfigurations, dimensions, materials, and/or structural considerationsfor capping plate 330 will depend on a given application and will beapparent in light of this disclosure.

As previously noted, system 1000 may be configured, in accordance withan embodiment, such that inner housing 300 can be caused and/orpermitted to rotate within outer housing 100 (e.g., within internalregion 120 thereof) through a given range of motion (discussed belowwith reference to FIG. 7). To assist with enabling inner housing 300 torotate within outer housing 100, one or more of an upper bridge assembly610 and/or a lower bridge assembly 620 may be included in system 1000.In one specific example embodiment, upper bridge assembly 610 may beconfigured to be operatively coupled with outer housing 100, forexample, between or otherwise proximate projections 330/340 (e.g., ascan best be seen from FIGS. 1A and 2A). In some cases, upper bridgeassembly 610 may be configured to pass over end surface 312 of innerhousing 300 (e.g., as can best be seen from FIGS. 2A and 2B), thuspermitting inner housing 300 to rotate there under. As will beappreciated, it may be desirable to provide upper bridge assembly 610with one or more fastening apertures 611 configured for receivingsuitable fasteners for operatively coupling upper bridge assembly 610with outer housing 100.

Also, lower bridge assembly 620 may be configured to be operativelycoupled with outer housing 100, for example, within internal region 120(e.g., as can best be seen from FIGS. 1B and 2B). In some cases, lowerbridge assembly 620 may be configured to be positioned adjacent cappingplate 333, thus permitting inner housing 300 to rotate there above. Aswill be appreciated, it may be desirable to construct upper bridgeassembly 610 and/or lower bridge assembly 620 from the same material(s)as outer housing 100, for example, to help minimize (or otherwisereduce) complications which otherwise may result from coefficient ofthermal expansion (CTE) mismatching. Other suitable configurationsand/or considerations for upper bridge assembly 610 and/or lower bridgeassembly 620 will depend on a given application and will be apparent inlight of this disclosure.

To further assist with enabling inner housing 300 to rotate within outerhousing 100, a drive shaft 630 may be included in system 1000. Inaccordance with an embodiment, drive shaft 630 may be configured to beoperatively coupled with inner housing 300. In one specific examplecase, a first portion of drive shaft 630 may be configured, for example,to be operatively coupled with end surface 312 of inner housing 300,while another portion of drive shaft 630 may be configured, for example,to be operatively coupled with capping plate 333. Thus, by virtue ofsuch operative coupling, and in accordance with an embodiment, rotationof drive shaft 630 may result in rotation of inner housing 300 withininternal region 120 of outer housing 100.

As can be seen from FIGS. 1B and 2B, for example, upper bridge assembly610 and/or lower bridge assembly 620 may be configured to receive atleast a portion of drive shaft 630. In some cases, one or morearrangements of bearings 640 may be included between drive shaft 630 anda given bridge assembly 610 and/or 620, for example, to assist withrotation of drive shaft 630. As will be appreciated in light of thisdisclosure, and in accordance with an embodiment, any of a wide varietyof bearings may be utilized. For instance, in one specific exampleembodiment, a given arrangement of bearings 640 may include duplexbearings, the inner hollow of which (e.g., formed by the inner racesthereof) may be configured to receive a portion of the drive shaft 630.

In one specific example embodiment, a duplex bearing arrangement may beincluded within each of upper bridge assembly 610 and lower bridgeassembly 620. In some such cases, one duplex bearing arrangement may beclamped axially within its corresponding bridge assembly (e.g., upperbridge assembly 610), while the other duplex bearing arrangement may beleft floating within its corresponding bridge assembly (e.g., lowerbridge assembly 620). In some other such cases, the duplex bearingarrangement in lower bridge assembly 620 may be clamped axially, whereasthe duplex bearing arrangement in upper bridge assembly 610 may be leftfloating. The decision as to which duplex bearing arrangement to allowto float, if any, may be based in part on which characteristics and/orbehaviors of the system 1000 are to be controlled. In either case,allowing one duplex bearing arrangement to float while clamping theother duplex bearing arrangement may accommodate coefficient of thermalexpansion (CTE) mismatching, if any, between the materials utilized inbearings 640 and the materials utilized in upper bridge assembly 610,lower bridge assembly 620, and/or drive shaft 630.

In some cases, drive shaft 630 may be operatively coupled, for example,with one or more azimuth positioning components. For instance, in someembodiments, drive shaft 630 may be operatively coupled with: (1) anazimuth motor 430; and/or (2) an azimuth encoder 440. When included,azimuth motor 430 may be configured to be positioned within outerhousing 100 (and/or optional housing base 210) and operatively coupled,for example, with the portion of drive shaft 630 within lower bridgeassembly 620. In accordance with an embodiment, azimuth motor 430 may beconfigured to engage drive shaft 630 to cause rotation thereof (e.g.,about the azimuth axis). By virtue of how drive shaft 630 may beoperatively coupled with inner housing 300 (e.g., at capping plate 330),rotation of drive shaft 630 via azimuth motor 430 may causecorresponding rotation of inner housing 300 within internal region 120of outer housing 100. When included, azimuth encoder 440 may beconfigured to be positioned on upper bridge assembly 610 (e.g., outsideof inner housing 300) and operatively coupled, for example with theportion of drive shaft 630 within upper bridge assembly 610. Inaccordance with an embodiment, azimuth encoder 440 may be configured tomeasure or otherwise determine the angular positioning of drive shaft630 (e.g., and thus inner housing 300, and thus mirror assembly 500). Insome cases, azimuth encoder 440 may be operatively coupled, for example,with electronic componentry (e.g., a computer or other data acquisitiondevice) configured to receive positioning/orientation data from azimuthencoder 440. As will be appreciated, such componentry may be configuredto subsequently transmit data/instructions to azimuth motor 430, forexample, to change the positioning/orientation of drive shaft 630 (e.g.,and thus inner housing 300, and thus mirror assembly 500). Othersuitable configurations and/or considerations for azimuth motor 430and/or azimuth encoder 440 will depend on a given application and willbe apparent in light of this disclosure.

As previously noted, and in accordance with an embodiment, system 1000can be configured to allow for inner housing 300 to rotate withininternal region 120 of outer housing 100 through any desired range ofrotational motion. For instance, consider FIG. 7, which is a top-downperspective view of a system 1000 configured in accordance with anembodiment of the present invention. As can be seen, inner housing 300may be provided with the ability to rotate through an angle α₁+α₂. Insome such cases, the value of angle α₁+α₂ may be defined, at least inpart, by virtue of a given configuration of system 1000 (e.g., by theconfiguration of upper bridge assembly 610, end surface 312, innerhousing 300, and/or projections 330/340, etc.). In one specific exampleembodiment, inner housing 300 may be permitted to rotate within outerhousing 100 through an angle α₁+α₂ in the range of less than or equal toabout ±40°. It should be noted, however, that the claimed invention isnot so limited, and a given system 1000 may be configured, in accordancewith an embodiment, to permit larger and/or smaller rotational rangesfor inner housing 300, as desired for a given target application.

In some cases, a desired range of motion may result from or otherwise beprovided by the physical structure/configuration of system 1000. Forinstance, as can be seen from the example embodiment of FIG. 7, endsurface 312 of inner housing 300 can be configured with one or morestopping features 313 which are designed to prevent further rotation ofinner housing 300 upon incidence with upper bridge assembly 610. In someother cases, azimuth motor 430 itself may be configured to provide thedesired range of motion. Numerous techniques for providing a desiredrange of motion will be apparent in light of this disclosure.

In some instances, inner housing 300 may be permitted to rotate freelywithin outer housing 100. In some other instances, inner housing 300 maybe permitted to rotate within outer housing 100 under the directionand/or application of an external force and/or component (e.g., azimuthmotor 430).

By virtue of how IMU 400 may be operatively coupled with inner housing300, which in turn may be operatively coupled with drive shaft 630,rotation of drive shaft 630 (e.g., by azimuth motor 430 and/or otherforce/component) may result in a corresponding rotation of IMU 400, forinstance, about the azimuth axis of system 1000. In some cases, and inaccordance with an embodiment, IMU 400 may be configured to account foreffects of such rotation, if any, on its measurements.

By virtue of how mirror assembly 500 may be operatively coupled withinner housing 300 (e.g., at projections 330/340), which in turn may beoperatively coupled with drive shaft 630, rotation of drive shaft 630(e.g., by azimuth motor 430 and/or other force/component) may result ina corresponding rotation of mirror assembly 500, for instance, about theazimuth axis of system 1000. Thus, as will be appreciated, IMU 400 andmirror assembly 500 may be made to rotate simultaneously about theazimuth axis of system 1000, in accordance with an embodiment.

As previously noted, it may be desirable to ensure that system 1000, inpart or in whole, includes environmental sealing provisions which mayhelp to protect internally housed optics/electronics from externalenvironmental hazards over a broad range of temperatures and/oroperating conditions. For example, system 1000 may be configured toprotect its internal volume from a variety of external environmentalhazards, such as, but not limited to: (1) water (e.g., rain, humidity,moisture, steam); (2) corrosive fluids/vapors (e.g., fuels,lubricants/greases, brake fluids, solvents, ozone); (3) particulates(e.g., dust, smoke); and/or (4) debris. In accordance with anembodiment, such environmental sealing provisions may be made, forexample, with respect to any of outer housing 100, inner housing 300,optional base assembly 200, and/or any other portion(s) of system 1000.

Also, as previously noted, it may be desirable to ensure that thevarious components of system 1000 are constructed of material(s) capableof use in a wide range of environments, temperatures, and/or stressors.Such materials may include, but are not limited to, titanium, steel,aluminum, etc. One or more of the various components of system 1000 maybe constructed of a single material or any combination of materials.Embodiments in which the various components are constructed of variedmaterials different from one another may be realized. Furthermore, oneor more components may be constructed of a single material or anycombination of materials thus making system 1000 suitable for use in thecontext of a wide range of environments, temperatures, and/or stressors.In some embodiments, all components of system 1000 may be made of asingle type of material to minimize or otherwise reduce coefficient ofthermal expansion (CTE) mismatch complications, if any.

In some embodiments, one or more of the various components of system1000 discussed above may be formed using techniques to ensure precisebalancing, alignment, orientation, etc., thereof. In some cases, one ormore components of system 1000 may be formed at the same time as anothercomponent to ensure a paired precision relationship. Such precisionformation may assist, for example, with reducing friction and thus heatwhich may be experienced by system 1000, thereby allowing for bettermaintenance of system accuracy.

The foregoing description of the embodiments of the invention has beenpresented for the purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed. Many modifications and variations are possible in light ofthis disclosure. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto.

What is claimed is:
 1. A system comprising: a first housing having afirst cavity provided therein; a second housing having a second cavityprovided therein, wherein the second housing is disposed within thefirst cavity and permitted to rotate therein; at least one of an upperbridge assembly and a lower bridge assembly, wherein said at least oneof the upper bridge assembly and the lower bride assembly is operativelycoupled to the second housing; an optical assembly operatively coupledwith the second housing; an inertial measurement unit (IMU) operativelycoupled with the second housing and positioned within the second cavityalong an axis of rotation of the first housing and the second housing; adrive motor operatively coupled with the second housing, via said atleast one of the upper bridge assembly and the lower bride assembly, andconfigured to cause rotation of the second housing; and a base assemblyoperatively coupled with the first housing, wherein the base assemblyincludes at least one of a thermal isolator and a power supplyinterface; wherein the rotation of the second housing results inrotation of the optical assembly and the IMU therewith.
 2. The system ofclaim 1, wherein rotation of the second housing is limited to a range ofless than or equal to ±40°.
 3. The system of claim 1, wherein theoptical assembly is permitted to rotate about at least one of anazimuthal axis of the system and an elevation axis of the system, andthe IMU is permitted to rotate about the azimuthal axis of the system.4. The system of claim 1, wherein the IMU is configured to account foreffects of rotation on measurements that it makes.
 5. The system ofclaim 1, wherein the IMU is a one-axis, two-axis, or three-axis IMU. 6.A system comprising: a first housing having a first cavity providedtherein; a second housing having a second cavity provided therein,wherein the second housing is disposed within the first cavity andpermitted to rotate therein; an inertial measurement unit (IMU)operatively coupled with the second housing and positioned within thesecond cavity along an axis of rotation of the first housing and thesecond housing; a mirror operatively coupled with the second housing; anelevation motor operatively coupled with the mirror and configured tocause rotation thereof about an elevation axis of the system; and anazimuthal motor operatively coupled with the second housing andconfigured to cause rotation thereof about an azimuthal axis of thesystem; wherein the rotation of the second housing results in rotationof the mirror and the IMU therewith about the azimuthal axis of thesystem.